1. Field of the Invention
The present invention relates to a method for reusing an image recording material used in electrophotographic recording or thermal transfer recording and a reusing apparatus therefor. More particularly, it relates to a method for reusing a reusable image recording material wherein image formation with an image forming material and removal thereof can be repeated by removing an image forming material from an image recording material on which the image forming material has been retained, and a reusing apparatus for reusing an image recording material.
2. Description of Related Art
Recently, global environmental destruction has come to light and the importance of forest resource conservation has been recognized; consequently, it has become an important subject to reduce the amount of wood resources utilized as raw materials of paper. For example, waste paper is not discarded as refuse and recycling thereof has been developed. Although the reuse of waste paper is an important means for recovering resources, there may be many problems in the preparation of reused paper. For example, recovery of waste paper has the following problems: leakage of confidential documents or data, particularly in enterprises; operation such as recovery of paper sorted with kinds of paper, and transportation thereof; and accumulating places for and control of recovered waste paper.
Further, reuse of waste paper may lead to deterioration in quality of reused paper since pulp fibers may be shortened during repulping of the waste paper. Further, a device for deinking from image areas is required. A paper machine itself is large, complex and expensive and, therefore, reuse of paper can not be done by an individual but can be effected only by certain enterprises. Unless the sorted recovery, transportation, accumulation and operation of a large device are performed efficiently, a large amount of energy will be consumed, i.e., the amount of CO.sub.2 discharged will be large. Consequently, the global warming phenomenon associated with the increase of the amount of CO.sub.2, which is one of global environmental problems, may further be accelerated.
As a solution for these problems, a method has been disclosed for erasing an image on a recording material, such as paper, once used to regenerate the material. The methods and apparatuses for removing an image on paper by a physical means include those disclosed in the following patent publications.
JP-A No. 1-101576 and JP-A No. 1-101577 disclose a method for reusing paper comprising immersing a sheet of paper or film on which an image forming toner has been deposited in an organic solvent in which the toner resin can be dissolved, and applying ultrasonic vibration thereto to release the toner dissolved in the solvent from the paper surface. In this method, however, the dissolved toner may penetrate again into the paper and stain the paper. Further, there are many other problems: undesired noise produced by the vibration; contamination in room due to the use of organic solvents; inflammability; and toxicity. This method is difficult to employ generally in homes and offices.
JP-A No. 4-349486 discloses that an image area or the entire surface of paper, on which the images have been recorded, is coated with an image forming material having the same color as the paper (e.g., white color toner). In this method, unlike peeling off an image portion from paper, the paper surface becomes glossy and the thickness of the paper is increased by repeating reuse. Consequently, the paper seems to be a special paper after reuse.
JP-A No. 6-208318, JP-A No. 6-250569, JP-A No. 6-250570, JP-A No. 6-266264, JP-A No. 6-273966, JP-A No. 6-289643 and JP-A No. 7-13383 disclose that a recording material such as paper on which an image is recorded is impregnated by dipping or spraying with a deinking agent (e.g., surfactant) solution, or that a solution of a water soluble polymer and a surfactant is coated on the surface or back surface of a recording material to penetrate into the recording material and the image forming material on the recording material is brought into contact with an image remover and heated to adhere with each other, and the image portion is peeled off from the recording material.
However, these methods also have many problems: organic solvents should be used; even if an aqueous solution is used, recording materials including paper are corrugated or wrinkled during drying. Paper may become transparent due to the surfactants or polymers which are not evaporated but accumulated during repeated use. In solid image where an image is formed on the whole surface of a recording material unlike a character image, the surfactant may hardly penetrate through the image forming material to reach the surface of the recording material. Therefore, the releasability of the image forming material from the paper as a recording material can not be enhanced. Consequently, the surface of the recording paper may be damaged upon peeling off since fibers of the surface of the paper may also be peeled off together with the image forming material. When a surfactant is penetrated from the back surface of a recording material, this method is difficult to apply to double-sided copied paper. Further, the apparatus can not be made compact since some space must be provided to contain and retain the solvent. Even if an aqueous solution is substituted for the organic solvent from the viewpoint of safety, maintenance cost for supplementing and purchasing the aqueous solution are required. A large amount of heat is required to evaporate and dry the moisture from a recording material paper. As a result, a large amount of energy consumption poses a high running cost.
JP-A 1-297294 discloses a cleaning method wherein a support comprising plastic, metal, liquid-impermeable paper or ceramic bearing an image thereon is used, and an image formed from a heat fusible ink on the support is removed from the support by heating an ink stripper through a heat fusible stripper. Thereafter, the ink stripper is cooled and the image is peeled off from the support. The support used in this method is a film or special paper which is quite different from usual paper in touch and feeling and is more expensive than the usual paper. The reason why any liquid-permeable paper can not be used as a support is that when the heat fusible ink is fused, the paper fibers are impregnated with the fused ink, the portion of which can not be stripped off. This method is time-consuming since cooling to room temperature is required before peeling off the image from the support. Further, since the heat fusible stripper and ink stripper are different from each other in their thermal expansion coefficients, they may separate from each other during cooling and some space is produced therebetween where the heat fusible ink can not be stripped off from the support.
Even if this problem may be solved by enhancing the adhesion strength between the heat fusible stripper and the ink stripper, the adhesion strength with the support is also enhanced and the support may be deformed and the force required to peel off will be extremely large. As a result, a drawback that this portion of the apparatus becomes large arises. Further, since an OHP film as an image bearing support generally used has an image receiving layer to enhance the fixing of an image forming material, it will also be difficult to peel off the OHP film from the ink stripper by the cooling and peeling method.